The trouble with cable splitters......

[HugoC]

Greetings all,

My Raven Twin tandem has S&S couplings and hence cable splitters for gear and rear brake cables fitted as standard. This allows me to dismantle the bike to get it in the car, in a bike box for air travel etc. So far, so good.

During uncoupling and reassembly of the bike, I take great care to minimise twisting the part of the cable splitter that fixes the cable with a grub screw, and I do not over tighten the grub screw in the splitter when replacing cables.

Despite these precautions, I find that the cable that is fixed to the splitter by the grub screw snaps too often. In 43000kms of riding the bike since new, the "front" cables, i.e., those connected to the Rohloff gear selector on the handlebar, have snapped a total of 4 times (always at the grub screw) whereas the "rear" cables have not yet snapped.

There must be a better way of using cable splitters to reduce the frequency of cables snapping. I'm trying to figure out how to add a nipple to the end of the cable after it has been fitted, and doing away with the grub screw altogether.

Has anyone any bright ideas?

[Danneaux]

Hi Hugo!

I'm not sure if this will work but back in the day, people would sometimes tin and solder the cut cable ends to prevent fraying rather than use crimped ends. I've done it myself, using a small torch and acid-flux solder for galvanized cables and, later, silver solder for stainless. It allowed for dis/re-assembly at the clamp bolt without having to replace the cable.

Now'days, I prefer using super glue, specifically beta-cyanocrylate to do the same. It not only binds the cut strands, it stiffens them for easy insertion and clamping without adding a lot of bulk.

Perhaps reinforcing the stranded wire (cable) in these or similar ways would prevent flattening, pinching, and fatigue stress at the grub screw inside the front cable splitter?

Might be worth a try. It has to be frustrating, replacing that cable so frequently.

Best, Dan.

[Danneaux]

Hugo, thinking a bit more about your problem, I'm wondering about the role of excess or repeated cable flex at or near the grub screw causing metal fatigue.

Of course, the rear splitter allows for actual un/screwing, as it is basically just a seat for the leaded end of the cable and this tolerates some "slop". The front splitter half is secured rigidly to the cable so any movement will be concentrated at the screw.

Besides reinforcing the stranded wire as I suggested earlier, is there something causing the front run of cable to bend and flex unduly? Something like a nearby cable stop or frame boss? Maybe a clamped-on accessory band? Is the anti-scratch o-ring still intact on the front half of the splitter? Is the cable end getting bent overmuch while the bike is disassembled or put into a case?

Just trying to think of possible contributors.

If your splitters have hex flats, it might be worth holding the front half stationary from twisting with a small wrench while you spin the freely turning rear half. I modified a small, automotive ignition points wrench for a friend's similar need and it seemed to do the trick for him.

EDIT 1: If you are using the J-TEK cable splitters without wrench flats, they're available in different lengths and for gear vs brake cables. I presume the difference is related to the size of the leaded cable end? Perhaps fitting a longer or shorter example -- if possible -- would ease stress on the cable. See...
https://www.sjscycles.co.uk/search/?term=j-tek%20cable%20splitter&geoc=US

EDIT 2: Is the cable splitter fitted midway in the open run of cable between stops? If the splitter is too close to the front stop, the cable will flex at greater angularity, right where it is clamped by the grub screw(s), resulting in metal fatigue and snapped cables.

Best, Dan.

[HugoC]

Thanks Danneaux for your helpful response.

I've tried creating a nipple of super glue around the end of some spare cable, and it does seem to work. Now, I just have to try this on the actual cable after it has been threaded through the splitter (I'm using the J-TEK splitter, which Thorn fitted to the bike).

The cable splitter lies approximately mid way between the cable stops when the Rohloff is in gear 7, so hopefully cable flex will be at a minimum. My tandem has the Ex box, so both cables run under the down tube to under the stokers seat tube, and onwards to the Ex box along the chain stay, which I believe is the optimal set up.

Once again thanks for your reply.

BR